Granular products containing disodium nitrilotriacetate and process for producing same



United States Patent 3,546,123 GRANULAR PRODUCTS CONTAINING DISODIUM NITRILLOTRIACETATE AND PROCESS FOR PRODUCING SAME Norman Earl Stahlheber, Columbia, Ill., and Chung Yu Shen, St. Louis, Mo., assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 709,877, Mar. 4, 1968. This application Apr. 15, 1969, Ser. No. 816,396

Int. Cl. Clld 3/04, 3/30, 11/00 US. Cl. 252-137 ABSTRACT OF THE DISCLOSURE Caking-resistant granular products are disclosed comprising from about 10% to about 87% by weight of the disodium salt of nitrilotriacetic acid and from about 1.5% to about 30% by weight of a soluble sodium salt of a second acid; the product having a bulky density of from 0.4 g./cc. to about 0.8 g./cc. and having greater than 50% of its particles larger than the openings in a US. Standard 80 mesh screen and smaller than the openings in a U8. Standard 4 mesh screen and having a pH in a 1% aqueous solution of above about 6. A process is also disclosed for producing the foregoing products comprising (1) forming a reaction mixture comprising (a) a water dispersible acidic material, (b) trisodium nitrilotriacetate and (c) from about 5% to about 25% by weight of water based upon the weight of the total reaction medium, said reaction medium having from about to about 100% of a molar equivalent amount of acidic material based upon the amount of trisodium nitrilotriacetate present in said reaction medium, (2) agglomerating the resulting mixture and (3) drying the resulting mixture to obtain the foregoing detergent additives. Typical water dispersible acidic materials include the fatty acids, alkyl sulfonic acids, alkyl aryl sulfonic acids, amino acids, organo-phosphoric acids, water-soluble inorganic acids and the acid salts of the foregoing acids. Detergent compositions containing the foregoing detergent additive are also disclosed.

This application is a continuation-in-part of application Ser. No. 709,877, filed Mar. 4, 1968, now abandonde.

This invention relates to a dry, free-flowing detergent product containing disodium nitrilotriacetate and processes for producing same.

The water-soluble salts of nitrilotriacetic acid are desirable detergent additives. Some problems exist with the incorporation of these materials into detergents. For example, essentially all of the commercial production of nitrilotriacetic acid salts is by the alkaline hydrolysis of nitrilotriacetonitrile to yield trisodium nitrilotriacetate. Trisodium nitrilotriacetate is powdery, dense, and hygroscope and when it is incorporated into detergent formulations, the detergents tend to cake. The problem with caking is so acute that moisture barriers such as plastic liners, wax coatings and aluminum foil are used in detergent cartons to prevent caking during storage. While the incorporation of moisture barriers into the detergent cartons is effective to prevent caking during storage, after the cartons are opened and subjected to relatively high humidity conditions, the detergent formulation will cake unless used relatively soon after opening. It is believed, therefore, that a caking-resistant product which is suitable for dry-blending with other detergent ingredients to form a detergent formulation which is equivalent to trisodium nitrilotriacetate as a detergent builder would be an advancement in the art.

12 Claims 3,546,123 Patented Dec. 8, 1970 Additionally, detergent slurries which contain trisodium nitrilotriacetate are very difficult to dry which generally results in a reduction of the plant production capacity and the production of a product having a very small particle size. A water-soluble nitrilotriacetate product with low bulk density and larger particle size which product can be mixed with other detergent ingredients to produce a detergent formulation will often increase the production rate of detergent plants and improve the product quality of detergent formulations.

In accordance with this invention it has been discovered that a caking-resistant granular product comprising from about 10 to 87 Weight percent of disodium nitrilotriacetate and from about 1.5% to about 30% by weight of a soluble sodium salt of another acid, and said product having a bulk density of about 0.4 g./cc. to about 0.8 g./cc. and having greater than about 50% of its particles larger than the openings in a US. Standard mesh screen and smaller than the openings in a US. Standard 4 mesh screen, a 1% solution of said product having a pH above about 6, have the foregoing desirable properties of caking-resistance and detergent building efficiency and can be dry-blended with other detergent ingredients to form highly desirable detergent formulations that do not cake eve under high humidity conditions. The foregoing highly desirable detergent additive is produced by (l) forming a reaction mixture comprising (a) a Waterdispersible acidic material, (b) trisodium nitrilotriacetate and (c) from about 5 to about 25 by weight of water based upon said reaction medium, the amount of said acidic material being from about 10% to about of a molar equivalent amount based upon the trisodium nitrilotriacetate present in said reaction medium, (2) agglomerating the resulting mixture and (3) drying the mixture thereby obtaining the granular caking-resistant product.

The term caking-resistant as used herein means that the composition shows no appreciably greater tendency to cake than spray dried detergent products which do not contain sodium nitriloacetate salts. For example, 50 gram samples after being placed in a cylindrical container and subjected to a relative humidity of 80% at 100 F. for 48 hours shows little evidence of caking; that is, upon screening with conventional screening techniques, essentially all the sample passes through a 6 mesh screen, U.S.S. sieve The term soluble in reference to the sodium salt of the other acid means that the salt is soluble under the conditions of use of detergents in laundry application. That is, at least 0.05 part of the sodium salt will dissolve in 100 parts of water at 25 C.

The suitable materials that can be used to convert at least about 10% of the trisodium nitrilotriacetate include the organic and inorganic acids and the acid salts thereof that can be either dissolved in Water or slurried in water and which will react with trisodium nitrilotriacetate under relatively high pH conditions. That is, essentially all water-soluble acids and acidic salts can be used since such acids and salts will convert the trisodium salt to the disodium salt. Additionally, some acids and salts are not sufficiently water-soluble to enable an equivalent amount of the acid or salt to be dissolved in the maximum of water that can be used in the process. In these instances, slurries or dispersions of the acidic material can be used. When the acid is in the liquid form, but is not readily dispersed in. water, as for example alkyl aryl sulfonic acid, the acid may be sprayed or otherwise dispersed directly into the reaction mixture simultaneously with a stream of water introduced through a separate spraying or distributing device. It is further necessary that the acidic materials form water-soluble sodium salts. It is to be noted that the term acidic materials as used herein refers to the capability of that material to ionize under reaction conditions to form a hydrogen ion. Typical inorganic acids which are useful in the practice of this invention include hydrochloric, sulfuric, orthophosphoric acid, pyrophosphoric acid, condensed phosphoric acid and the like. Furthermore, acidic salts of the foregoing acids such as sodium acid pyrophosphate and potassium acid pyrophosphate can be used.

Useful organic acids include the mono and polycarboxylic acids, organophosphonic acids, organic sulfonic acids and acidic salts of the organic acids which have more than one acid group. It is especially preferred to use the acids that form water-soluble salts that are commonly used in detergent products such as the alkyl or alkyl aryl sulfonic acids, fatty acids and organo-phosphonic acids and polycarboxylic acids. Typical examples of sulfonic acids which can be used in the practice of this invention include the alkyl and alkyl aryl sulfonic acids containing from about to about 30 carbon atoms in the alkyl group. Useful alkyl aryl sulfonic acids can be represented by the formula:

wherein A is an aryl group generally selected from the group consisting of phenyl or naphtha and R is an alkyl group, either straight or branched chain containing from about 1 to about 30 carbon atoms. Typical examples of the foregoing sulfonic acids include toluene sulfonic acid, dodecylbenzene sulfonic acid, tetradecylbenzene sulfonic acid, octadecylbenzene sulfonic acid, decylnaphthalene sulfonic acid and mixtures thereof. It is to be noted that although the foregoing acids are described as having a specified number of carbon atoms in their alkyl group, it is to be understood that in most instances under conventional means of manufacture that generally mixtures of compounds having an average alkyl chain length of the specified value are produced. For example, the acid can be known as dodecylbenzene sulfonicacid although the material is a mixture of alkyl benzene sulfonates having an alkyl chain length varying from about 10 to about 14 carbon atoms with an average chain length of about 12.

The alkyl sulfonic acids and fatty acids having from 1 to 30 carbon atoms can be used in the practice of this invention. Generally, it is preferred to use those having from about 8 to about 24 carbon atoms since the watersoluble salts thereof have detergency properties. Typical examples include dodecyl sulfonic acid, nonyl sulfonic acid, octadecyl sulfonic acid, octyl sulfonic acid and the like.

Other aminopolycarboxylic acids and their acidic salts can be used to convert trisodium nitrilotriacetate to disodium nitrilotriacetate. Typical suitable aminopolycarboxylic acids can be represented by the formula:

N-omooolr where R is a member selected from the group consisting of the radicals CHzCOOU.

and

011 00011 (311200011 CzH4l I-C H N where R is a member selected from the group consisting of lower alkyl (14 carbon atoms), hydroxy substituted lower alkyl, phenyl and hydroxy substituted phenyl, and R is a member selected from the group consisting of lower alkyl (l4 carbon atoms), and hydroxy substituted lower alkyl, represents typical aminocarboxylic acids which can be used.

Compounds illustrative of the foregoing amino polycarboxylic acids include ethylenediamine tetra-acetic acid, diethylenetriamine penta-acetic acid, 1:2:diaminocyclohexane tetraacetic acid, hydroxyethyl amino diacetic acid, ethylene diamine triacetic acid, orthohydroxyl phenyl ethylene diamine triacetic acid, anthranilic-N-N-diacetic acid, tris (hydroxymethyl) diethylene triamine diacetic acid, C-dibutyl-nitrilotriacetic acid and C-cyclohexenylnitrilotriacetic acid.

The amino tri (lower alkylidenephosphonic acids) are in another class of acids with desirable properties of sequestering metal ions and can be used in the present invention. Typical of the class of compounds useful in this invention can be represented by the formula Y OH 3 where X and Y are members selected from the group consisting of hydrogen and lower alkyl group (1-4 carbon atoms).

Compounds illustrative of amino tri(lower alkyldenephosphonic acids) include:

Amino tri (methylenephosphonic acid) Amino tri (ethylidenephosphonic acid) Amino tri (isopropylidenephosphonic acid) Amino tri (butylidenephosphonic acid) Amino tri (propylidenephosphonic acid) Amino tri (tert-amylidenephosphonic acid) Amino tri (isoamylidenephosphonic acid) Amino tri (sec butylidenephosphonic acid).

Suitable alkylene diphosphonic acids for the successful practice of this invention can be represented by the where X is a member selected from the group consisting of hydrogen and lower alkyl group (l4 carbon atoms), Y is either hydrogen, hydroxyl, a halogen, especially chlorine, bromine and fluorine, or lower alkyl group (1-4 carbon atoms), and n is an integer from 1 to 6.

Compounds illustrative of alkylene diphosphonic acids include:

Methylenediphosphonic acid Ethylidenediphosphonic acid 1 hydroxyl, ethylidenediphosphonic acid Hexamethylenediphosphonic acid Isopropylidenediphosphonic acid Butylidenediphosphonic acid Hydroxylmethylenediphosphonic acid 1 hydroxyl, propylenediphosphonic acid Amylidenediphosphonic acid Tri(Z-hydroxy, 3 methyl, 4 bromo 4 hexylidene) diphosphonic acid Pentamethylenediphosphonic acid Penta (propylidene) diphosphonic acid Tetra (l-hydroxyethylidene) diphosphonic acid Hexa (Z-hexylidene) diphosphonic acid Tri (Z-hydroxy, 3 amylidene) diphosphonic acid Tetra (2 amylidene) diphosphonic acid Di (2 methyl, 3 hexylidene) diphosphonic acid Tetra (4 octylidene) diphosphonic acid Penta (2 propylidene) diphosphonic acid Tri (Z-hydroxy, 3 methyl, 4 chloro, 4 butylidene) diphosphonic acid.

Highly concentrated aqueous solutions of the foregoing acids can be used in some cases, and when using a sulfonic acid, concentrations even as high as essentially 100% may be used. However, in order to avoid local over concentrations of acid which can cause the formation of the water-insoluble nitrilotriacetic acid, it is desirable when using the higher acid concentrations, for example, above 75%, also to use an auxiliary spray of water. The desired acid concentration depends on the type of acid required and the final disodium nitrilotriacetate concentration, the optimum condition is such that the moisture (water) level of the reaction mixture is high enough to give efficient granulation and reaction but the moisture level must be below the slushy state to avoid handling difficulties in processing. The desired water content is about 5 to about 25 percent by weight based on the weight of the total reaction medium. For example when sulfuric acid is used to prepare a final mixture with a molar ratio of acid to trisodium nitrilotriacetate monohydrate of about 1:3, the desired acid concentration is about 50 percent to give about 14.8% water content of the total weight of reaction medium. When the water content is increased to about 30%, a slushy state is developed. The lowest water content of about 5% is established when a dodecylbenzene sulfonic acid is used. In most instances, it is preferred to have an acid concentration of from about 30 to 75 percent by weight with a 50% solution being preferred.

When acid salts of the acids are used, a relatively uniform mixture of the trisodium nitrilotriacetate and the acid salt and then the required amount of water can be sprayed onto a bed which is being agitated by conventional means such as in a rotating drum. Solutions or aqueous slurries of the acid salts can also be used if desired.

In most instances, under preferred conditions, a relatively high yield of product having a particle size of 4 to +80 (US. Standard mesh screen size) can be obtained. The foregoing screen size enables the product to be blended with conventional spray dry detergents to form a formulated dry detergent having highly desirable properties. Yields of this preferred screen size in excess of 60% can be achieved in a single operation. A higher yield, that is, up to about 90%, can be achieved by reducing the oversized material to -4 mesh. The watersolubility of the products of the present invention is excellent, that is, essentially no water-insoluble material is present when grams of the product are mixed with 100 grams of water at C. If desired, other builder salts can be incorporated into a trisodium nitrilotriacetate prior to its acidification. For example, the sodium salts of 1 hydroxy ethylidene 1,1-diphosphonic acid can be added to yield a formulated builder material which has a desirable characteristic. It is to be noted that the bulk density of the product of this invention ranges from 0.4 g./ cc. to 0.8 g./cc. which enables the product to be dry-blended with a conventional spray-dried detergent or with other dry detergent ingredients.

The agglomeration of the reaction mixture is carried out generally by agitating a bed of the trisodium nitrilotriacetate. In most instances, it is preferred to spray an aqueous mixture of a suitable acid onto a bed of trisodium nitrilotriacetate which is in a rota-ting drum or vibrating conveyor or the like. Generally, a rotating drum provided with a source of heat is preferred since only one piece of equipment is needed. If desired, however, the aqueous solution of the acid can be evenly distributed over a volume of trisodium nitrilotriacetate and subsequently dried in any conventional drier for dry- 6 ing particulate solids such as tray driers, rotary driers, tunnel driers, and the like.

The composition of this invention can be used with any of the anionic, nonionic or amphoteric type synthetic surface active agents and mixtures of these surface active agents. For example, it can be blended with various spraydried surfactants containing anionic synthetic surface active agents.

Anionic synthetic surface active agents, that is nonsoap detergents, are generally described as those compounds which contain hydrophilic and lyophilic groups in their molecular structure and ionize in an aqueous medium to give anions containing both the lyophilic group and hydrophilic group. The alkyl aryl sulfonates, the alkane sulfates and sulfated oxyethylated alkyl phenols are illustrative of the anionic type of surface active compounds.

The alkyl aryl sulfonates are a class of synthetic anionic surface active agents and can be represented by the formula b)"1' Q s )"2 where R is hydrogen or a straight or branched chain hydrocarbon group of from 1 to 4 carbon atoms; R is a straight or branched chain hydrocarbon radical having from about 1 to about 24 carbon atoms, at least one R having at least 8 carbon atoms; n is from 1 to 3; n is from 1 to 2; Ar is a phenyl or a naphthyl radical and M is either hydrogen, an alkali metal, such as sodium, potassium, and the like; ammonium, or an organic amine such as ethanol amine, diethanol amine, triethanol amine and hexylamine and the like. R can be, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and the like. R can be, for example, methyl, ethyl, hexyl, octyl, tertoctyl, iso-octyl, nonyl, decyl, dodecyl, octadecyl, and the like,

Compounds illustrative of the alkyl aryl sulfona-tes include sodium dodecylbenzene sulfonate, sodium decylbenzene sulfonate, ammonium methyl dodecylbenzene sulfonate, ammonium dodecylbenzene sulfonate, sodium octadecylbenzene sulfonate, sodium nonylbenzene sulfonate, sodium dodecylnaphth'alene sulfonate, sodium heptadecylbenzene sulfonate, notassium eicocosyl naphthalene sulfonate, ethylamine undecylnaphthalene sulfonate and sodium docoxylnaphthalene sulfonate.

The alkyl sulfates are a class of synthetic anionic surface active agents and can be represented by the formula RSO M, wherein M is either hydrogen, an alkali metal, such as sodium, potassium and the like, ammonium or an organic amine, such as ethanolamine, diethanolamine, triethanolamine, ethylenediamine and diethylenetriamine, and the like; and R is a straight or branched chain saturated hydrocarbon radical, such as octyl, decyl, dodecyl,

w the general formula where R is a straight or branched chain saturated hydrocarbon group having from about 8 to about 18 carbon atoms, such as a straight or branched group, such as octyl, nonyl, decyl, dodecyl, and the like; A is either oxygen, sulfur, a carbonamide group, thiocarbonamide group, a carboxylic group or thiocarboxylic ester group, x is an integer from 3 to 8 and M is either hydrogen, or an alkali metal such as sodium, potassium, and the like, or ammonium, or an organic amine, such as ethanolamine, diethanolamine, triethanolamine, ethylene diamine, and the like.

Compounds illustrative of the sulfated oxyethylated alkyl phenol class of anionic surface active agents include ammonium nonylphenoxy tetraethyleneoxy sulfate, sodium dodecylphenoxy triethyleneoxy sulfate, ethanolamine decylphenoxy tetraethyleneoxy sulfate and potassium octylphenoxy triethyleneoxy sulfate.

Nonionic surface active compounds can be broadly described as compounds which do not ionize but acquire hydrophilic characteristics from an oxygenated side chain such as polyoxyethylene and the lyophilic part of the molecule may come from fatty acids, phenol, alcohols, polyalcohols, amides or amines. The compounds are usually made by reacting an alkylene oxide such as ethylene oxide, butylene oxide, propylene oxide and the like with fatty acids, a straight or branched chain alcohol, phenols, thiophenols, amides and amines to form polyoxyalkylene glycol ethers and esters, polyoxyalkylene alkyl phenol and polyoxyalkylene thiophenols, and polyoxyalkylene amides and the like. It is generally preferred to react from about 3 to about 30 moles of alkylene oxide per mole of the fatty acids, alcohols, phenols, thiophenols, amides or amines. Additionally, the long chain tertiary amine oxides and the long chain phosphine oxides and the dialkyl sulfoxides can be used.

Illustrative of these synthetic nonionic surface active agents are the products obtained from the reaction of alkylene oxide with an aliphatic alcohol having from 8 to 18 carbon atoms, such as octyl, nonyl, decyl, octadecyl, dodecyl, tetradecyl, and the like; with an alkyl phenol in which the alkyl group contains between 4 and 20 carbon atoms, such as butyl, dibutyl, amyl, actyl, dodecyl, tetradecyl, and the like; and with an alkyl amine in which the alkyl group contains between 1 to 8 carbon atoms.

Compounds illustrative of synthetic nonionic surface active agents include the products obtained from condensing ethylene oxide or propylene oxide with the following: propylene glycol, ethylene diamine, diethylene glycol, dodecyl phenol, nonyl phenol, tetradecyl alcohol, N- octadccyl diethanolamide, and N-dodecyl monoethanolamide.

Long chain tertiary amine oxides corresponding to the following general formula, R R R N O, wherein R is an alkyl radical of from about 8 to 18 carbon atoms, and R and R are each methyl or ethyl radicals. The arrow in the formula is a conventional representation of a semipolar bond. Examples of amine oxides suitable for use in this invention include dimethyldodecylamine oxide, dimethyloctylamine oxide, dimethyldecylamine oxide, dimethyltetradecylamine oxide, and dimethylhexadecylamine oxide.

Long chain tertiary phosphine oxides corresponding to the following formula RR'R"P 0, wherein R is an alkyl, alkenyl or monohydroxyalkyl radical ranging from 10 to 18 carbon atoms in chain length and R and R are each alkyl or monohydroxyalkyl groups containing from 1 to 3 carbon atoms. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of suitable phosphine oxides are:

Dimethyldodecylphosphine oxide, Dimethyltetradecylphosphine oxide, Ethylmethyltetradecylphosphine oxide, Cetyldimethylphosphine oxide, Dimethylstearylphosphine oxide, Cetylethylpropylphosphine oxide, Diethyldodecylphosphine oxide, Diethyltetradecylphosphine oxide, Bis(hydroxymethyl)dodecylphosphine oxide, Bis(2-hydroxyethyl)dodecylphosphine oxide, 2-hydroxypropylmethyltetradecylphosphine oxide,

8 Dimethylolethylphosphine oxide, and Dimethyl-Z-hydroxydodecylphosphine oxide.

Dialkyl sulfoxides corresponding to the following formula, RRS O, wherein R is an alkyl, alkenyl, betaor gamma-monohydroxyalkyl radical or an alkyl or betaor gamma-monohydroxyalkyl radical containing one or two other oxygen atoms in the chain, the R groups ranging from 10 to 18 carbon atoms in chain length, and wherein R is methyl or ethyl. Examples of suitable sulfoxide compounds are:

Dodecylmethyl sulfoxide Tetradecyl methyl sulfoxide 3-hydroxytridecyl methyl sulfoxide 2-hydroxydodecyl methyl sulfoxide 3-hydroxy-4-decoxybutyl methyl sulfoxide 3-hydroxy-4-dodecoxybutyl methyl sulfoxide 2-hydroxy-3-decoxypropyl methyl sulfoxide 2-hydroxy-3-dodecoxypropyl methyl sulfoxide Dodecyl ethyl sulfoxide Z-hydroxydodecyl ethyl sulfoxide.

The 3-hydroxy-4-decoxybutyl methyl sulfoxide has been found to be an especially effective detergent Surfactant. An outstanding detergent composition contains this sulfoxide compound in combination with the builder compound of this invention.

Amphoteric surface active compounds can be broadly described as compounds which have both an anionic and cationic group in their structure. Illustrative of the amphoteric urface active agents are the amido alkane sufonates which are represented by the general formula where M is either hydrogen, an alkali metal, such as sodium, potassium, and the like or ammonium, n is an in teger from 1 to 5, R is an alkyl radical with from 8 to 18 carbon atoms, and R is a member selected from the group consisting of hydrogen, alkyl, aryl or alicyclic radicals.

For example, the C-aliphatic substituted, N-aliphatic substituted, amido alkyl sulfonates are illustrative of the amido alkane sulfonates. Compounds illustrative of these include: sodium C-pentadecyl, N-methyl amido ethyl sulfonate; sodium C-tridecyl, N-methyl amino ethyl sulfonate; ammonium C- decyl, N-dodecyl amido pentyl sulfonate; potassium C-hexadecyl, N-propyl amido propyl sulfonate; and potassium C-tridecyl N-hexyl amido methyl sulfonate.

In addition the C-aliphatic substituted, N-aryl substituted, amino alkyl sulfonates are illustrative of the amido alkane sulfonates. Compounds illustrative of these include: sodium C-dodecyl N-benzene amido methyl sulfonate; potassium C-octyl N-naphthalene amido propyl sulfonate; sodium C-hexadecyl N-benzene amido pentyl sulfonate and ammonium C-tetradecyl N-naphthalene amido methyl sulfonate.

Also the C-aliphatic substituted, N-cycloalkyl substituted, amino alkyl sulfonates are illustrative of the amido alkane sulfonates. Compounds illustrative of these include: sodium C-dodecyl, N-cyclopropyl amido methyl sulfonate; potassium C-tetradecyl, N-cyclohexyl amido ethyl sulfonate; ammonium C-decyl, N-cyclopropyl amido butyl sulfonate and sodium C-octyl, N-cyclohexyl amido methyl sulfonate and the like.

Zwitterionic synthetic detergents can be broadly described as derivatives of aliphatic quaternary ammonium compounds in which the aliphatic radical may be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group. Examples of compounds falling within this definition are 3-(N,N-dimethyl-N-hexadecylammonio) 2 hydroxypropane-l-sulfonate which are especially preferred for their excellent cool water detergency characteristics.

The anionic, nonionic, ampholytic and zwitterionic detergent surfactants mentioned above can be used singly or in combination in the practice of the present invention. The above examples are merely specific illustrations of the numerous detergents which can find applications within the scope of this invention.

Other illustrative surface active agents can be found in Schwartz and Perry, Interscience Publishers, New York, Surface Active Agents, vol. I (1949) and vol. II (1958), which are incorporated herein by reference.

In addition to the foregoing surface active agents, in most instances other detergent additives will be used, such as the well-known phosphate detergent builders such as sodium tripolyphosphate, tetrasodium pyrophosphate, sodium and potassium sulfates and carbonates, sodium silicate, optical brighteners, corrosion inhibitors, antiredeposition agents, dyes and pigments. Generally a formulated detergent base containing mixtures of the foregoing detergent additives and surface active agents will be prepared in a conventional manner such as by the conventional spray drying techniques or by the preparation of a detergent base utilizing the reaction of sodium hydroxide and sodium trimetaphosphate to produce a material containing the normal detergent additives, a surface active agent and a sodium tripolyphosphate hexahydrate as is disclosed in U.S. Pat. 3,390,093.

The foregoing detergent additives will generally be blended with the composition of this invention to yield a detergent composition having from about 2% to about 35% by weight of nitrilotriacetates calculated on the basis of nitrilotriacetic acid. Preferred ranges are usual- 1y from about 5 to about 25% by weight calculated as nitrilotriacetic acid.

To further illustrate this invention, the following nonlimiting examples are presented. All parts, proportions and percentages are by weight unless otherwise indicated.

EXAMPLE 1 About 1000 parts of trisodium nitrilotriacetate monohydrate having 90% of its particles smaller than the openings in the US Standard 60 mesh screen are charged into a rotary dried. About 235 parts of a 50% aqueous solution of sulfuric acid are added through a spray nozzle to give essentially an even distribution over the tumbling bed of trisodium nitrilotriacetate. The molar ratio of sul-. furic acid to trisodium nitrilotriacetate is about 1:3. The material agglomerates to firm, porous granules when the sulfuric acid is added. The product is dried at 150 F. by passing hot air through the drier while the drier is rotating. After the product is dried, a sample has the following screen analysis:

The bulk density of the -12 to +40 mesh fraction is about 0.55 g./ cc. A IO-gram sample of the product completely dissolves in 100 grams of water at 25 C. indicating no appreciable conversion of the trisodium nitrilotriacetate to nitrilotriacetic acid. The pH of a 1% aqueous solution of a sample of the foregoing granular material is about 9.3. No caking is observed in samples of the granular material which are stored in air having a relative humidity of 80% at 100 F. for 48 hours. By comparison, samples of the trisodium nitrilotriacetate forms hard lumps when stored under identical conditions at 80% RH or even as low as 70% RH. Analysis of a sample of the granular product indicates that the composition is equivalent to about 30.3% trisodium nitrilotriacetate, about 52.8% disodium nitrilotriacetate and about 15.9% sodium sulfateand about 1% water indicating that essentially all of the sulfuric acid reacted with the trisodium nitrilotriacetate.

About 100 parts of the granular product having the 10 --12 to +40 screen size is blended in a ribbon blender with 900 parts of a spray-dried detergent composition containing as an anionic active, sodium tetradecyl benzene sulfonate, and other detergent additives such as sodium tripolyphosphate, sodium carboxymethyl cellulose, additional sodium sulfate and a corrosion inhibitor. After blending for suflicient time to produce a relatively uniform blend, the detergent formulation is suitable for packaging in standard containers without a moisture barrier. The product is a high quality heavy-duty laundry detergent.

EXAMPLE 2 Using essentially the same equipment and procedure as in Example about 1000 parts of trisodium nitrilotriacetate monohydrate are charged into the rotary calciner. About 240 parts of an aqueous solution containing about 75% by weight of sulfuric acid are added as in Example 1. A sulfuric acid to trisodium nitrilotriacetate molar ratio of about 1:2 is used. Based on reactants the moisture content is 10%. After drying, about 50% of the product is in the desired '12 to +40 mesh size, however, essentially no water-insoluble material is present when a sample is tested as in Example 1.

Following essentially the same procedure as above only using 183 parts 98% sulfuric acid aqueous solution to give a total water content of 5.7% based on reactants resulted in local over concentration of acid with low yields of product having the desired particle size and high water insolubles thus indicating some conversion to nitrilotriacetic acid.

Following essentially the same procedures as above only using 720 parts of 25% sulfuric acid aqueous solution resulted in the formation of a slurry containing about 35 water based on reactants. The slurry is difficult to handle.

EXAMPLE 3 About 770 parts of trisodium nitrilotriacetate monohydrate having essentially the same particle size as the trisodium nitrilotriacetate used in Examples 1 and 2 were charged into a ribbon blender. About 160 parts of a 20% U.S. Standard Screen Mesh: Percent +12 15 12 to +60 60 5 An analysis of a sample of the product indicates the following:

Percent Trisodium nitrilotriacetate 65.9 Disodium nitrilotriacetate 27.4 Sodium chloride 6.7

The bulk density measured on a sample of the product was about 0.5 g./cc. The product having the -12 to +60 particle size is suitable for dry-blending with a detergent composition as a builder. The product is caking-resistant when a sample is tested under conditions specified in Example 1. Essentially no caking is observed on samples of the detergent containing the above product at levels up to about 20% by weight and containing nonionic surface active agents such as ethoxylated ethers or nonyl phenol and other detergent additives such as sodium tripolyphosphate, sodium sulfate, carboxymethylcellulose and sodium silicate.

EXAMPLE 4 About 1000 parts of anhydrous trisodium nitrilotriacetate are charged to a rotary drier. About 200 parts of dodecylbenzenesulfonie acid and 63 parts of water are sprayed simultaneously through separate spray nozzles to 1 1 give essentially an even distribution over the rolling bed of trisodium nitrilotriacetate. The molar ratio of sulfonic acid to trisodium nitrilotriacetate is about 1 to 6 and the final moisture content is about 5% after drying in a tray drier and breaking up loose agglomerates, a sample has the following screen analysis.

US Standard Screen: Percent +12 mesh 1 12+60 90 -60 9 A sample of the material indicates that the molar ratio of sodium dodecylbenzene sulfonate to disodium nitrilotriacetate to trisodium nitrilotriacetate is 1:1:5, respectively.

Substantially similar results are achieved when molar equivalent amounts of the fatty acids and alkyl sulfonic acid are substituted for the dodecylbenzene sulfonic acid used in this example. The products produced are free flowing and caking-resistant when tested as specified in Example 1.

EXAMPLE 5 About 2690 parts of trisodium nitrilotriacetate monohydrate and 374 parts of sodium tripolyphosphate are charged to a rotary calciner. About 687 parts of 60% hydroxy ethylidene diphosphonic (HEDP) acid solution are sprayed over the rolling bed of sodium tripolyphosphate and trisodium nitrilotriacetate. As the resultant mixture is agglomerated and dried, a porous, granular product is produced. The resulting granular product contains approximately the following proportions of salts:

Wt. percent anhydrous basis Trisodium NTA 29.6

Disodium NTA 42.7 Trisodium HEDP 16.4 Sodium tripolyphosphate 11.3

The product density is 0.55 gram per cc. and 100 parts is suitable for blending with about 1000 parts of a spray dried detergent containing about 25% sodium dodecylbenzene sulfonate, about 40% sodium tripolyphosphate,

30% sodium sulfate and about 5% of other additives such as carboxymethylcellulose, sodium silicate, dyes, brighteners and the like.

EXAMPLE 6 When Example 5 is repeated except with anhydrous trisodium nitrilotriacetate a similar useful product is obtained.

What is claimed is:

1. A process for producing a granular product containing the disodium salt of nitrilotriacetic acid comprising forming a reaction mixture consisting essentially of (a) a water dispersible acidic material selected from the group consisting of sulfuric acid, hydrochloric acid, phosphonic acids, sulfonic acids, polycarboxylic acids, orthophosphoric acid, pyrophosphoric acid, condensed phosphoric acids, acidic sodium and acidic potassium salts of said acids and mixtures thereof; (b) trisodium nitrilotriacetate; and water; said water constituting from about to about 25 of said reaction medium, the amount of said acidic material being from about 10% to about 100% of the amount theoretically required to convert all of said trisodium nitrilotriacetate to disodium nitrilotriacetate, converting from about 10% to about 100% of said trisodium nitrilotriacetate to disodium nitrilotriacetate and forming a water-soluble sodium salt of said acidic material, agglomerating and drying the resulting mixture thereby forming a caking-resistant granular product comprising disodium nitrilotriactate and a watersoluble sodium salt of said acidic material and having greater than 50% of its particles larger than the openings in a US. Standard 80 mesh screen and smaller than the openings in a US. Standard 4 mesh screen and having a bulk density of 0.4 g./cc. to 0.8 g./cc.

2. A process according to claim 1 wherein said acidic material is an aqueous solution of an inorganic acid having a concentration of acidic material from about 30% to about by weight.

3. A process according to claim 2 wherein said acidic material is sulfuric acid.

4. A process according to claim 2 wherein said acidic material is a phosphonic acid.

5. A process according to claim 1 wherein said acidic material is a sulfonic acid.

6. A water-soluble caking-resistant granular product consisting essentially of (a) from about 10 to about 87 weight percent of the disodium salt of nitrilotriacetic acid, (b) from about 1.5% to about 29.5% by Weight of a soluble sodium salt of a second acid selected from the group consisting of sulfuric acid, hydrochloric acid, sulfonic acids, phosphonic acids, polycarboxylic acids, orthophosphoric acid, pyrophosphoric acid, condensed phosphoric acids, acidic potassium and acidic sodium salts of said acids and mixtures thereof and (c) from about 0 to about 88.5% by weight of trisodium nitrilotriacetate, said product having greater than 50% of its particles larger than the openings in a US. Standard mesh screen and smaller than the openings in a US. Standard 4 mesh screen and having a bulk density of 0.4 g./cc. to 0.8 g./ cc.

7. A product according to claim 6 wherein said second acid is sulfuric acid.

8. A product according to claim 6 wherein said second acid is a phosphonic acid.

9. A product according to claim 6 wherein said second acid is a sulfonic acid.

10. A detergent composition consisting essentially of (a) a surface active agent selected from the group consisting of anionic, nonionic, amphoteric surface active agents and mixtures thereof, and (b) the water soluble caking-resistant granular product according to claim 6, said detergent composition having from about 2% to about 35% by weight of nitrilotriacetates calculated on the basis of nitrilotriacetic acid.

11. A detergent composition of claim 10 wherein said sodium salt of said second acid is selected from the group consisting of sodium sulfate, sodium chloride, sodium phosphates and mixtures thereof.

12. A detergent composition of claim 10 wherein said sodium salt of said acid is sodium sulfate.

References Cited UNITED STATES PATENTS 12/1967 Gedge 252l37 11/1967 Behrens 252-137 US. Cl. X.R.

2923; UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. a,s +s,123 Dated December :22 1970 Norman Earl Stahlheber and Chum? Yu Shen Inventor( s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 2 the word "Nitrillotriacetate" is incorrect] soelled, it should read NITRILOTRIACETATE Column 2 line 45 after the word "sieve" should appear the word series.

Column 4, line 3, the word "alkyldene" should be alkylide Column 8 line 73 one entire line was omitted following the words "definition are" and should read 3-(N,N-dimethvl-N- hexadecvlammonio)nronane-l-sulfonate and Column 10 line 1H the word "Examole" should be followed wit the numeral --'1 Signed and sealed this 6th day of June 1972.

(SEAL) Attest:

EDWAR'D M.FLETCHER,JR. Attesting Officer ROBERT GOTTSCHALK Commissioner of Patents 

